The present invention generally relates to handheld power tools.
Relatively small handheld power tools that have a rotating output shaft include those that are known as spiral cutting tools and are used by tradesmen, particularly in the construction trades. Such spiral cutting tools utilizes a spiral bit that has a sharp cutting edge that is configured in a spiral around an axis of the bit and is designed to cut materials perpendicular to the axis of a bit. They are often used by contractors to cut holes in drywall for electrical outlets, switches as well as other components such as duct work, vents and the like. The spiral cutting tools operate much like a router and are often referred to in the trades as handheld router tools. The tools are conveniently sized to be held in one hand by a user and are relatively high powered for their size and operate at high rotating speeds. Because they are relatively lightweight, they are powered by a cord rather than by a relatively heavy power pack design.
Because they are often used to cut drywall, they are commonly equipped with a depth guide so that the cutting bit does not penetrate much beyond the opposite side of the material which they are cutting. Because cuts are often made at corners or other inconvenient locations, it is desirable to have the depth guide be relatively small in size so that it does not appreciably decrease the ability of the operator to see exactly where he is cutting. It is also desirable that it not interfere appreciably with a collet that the operator may need to manipulate to remove and replace spent tool bits.
Operators often use a pencil to draw an outline of the cut that is to be made, but even if that is not done, operators often use the tool in a free hand manner to cut a precise rectangle or other shape to expose an electrical outlet or switch and such free hand operation requires the operator to be able to see what is being cut.
Improvements in the design of such tools continues to be the subject of research and engineering efforts.